The present invention relates generally to medical devices and more particularly to a device and method for navigating a catheter through a body passageway. In one preferred embodiment, the invention involves navigating a peripherally inserted central catheter to the superior vena cava and positioning the peripherally inserted central catheter within the superior vena cava or right atrium for treatment. In another preferred embodiment, the invention involves transmitting light through the tubular wall of a catheter and overlying body tissues for external navigation, where the tubular wall of the catheter is made of a material that absorbs certain wavelengths of light and the light source emits light within a limited wavelength range that is transmissable through the light absorbing material.
One type of central venous catheter is referred to as peripherally inserted central catheters (“PICC”), which are commonly used for infusing drugs or nutrition into a patient's body and for venous pressure monitoring, blood sampling, administration of fluids, and for the delivery of contrast solution for imaging studies. As those of ordinary skill in the art understand the distal portion of a PICC is typically positioned within the superior vena cava of a patient. Although various locations may be prescribed for the distal end of the PICC, one common position where the distal end of the PICC may be located is the lower one third of the superior vena cava. The use of PICCs in the superior vena cava is desirable for a number of treatments since the entire blood flow through a patient's body passes through the superior vena cava to the heart, and is then recirculated through the patient's body. As a result, drugs and nutrition infused into the superior vena cava are quickly diluted and evenly distributed throughout the patient's body.
For example, chemotherapy drugs, and other such drugs, are often released into the body through a PICC to the superior vena cava. The superior vena cava is particularly advantageous for the release of chemotherapy drugs because chemotherapy drugs can be harmful to the tissues of the vessel walls. However, because of the high flow rate of blood in the superior vena cava, chemotherapy drugs are less likely to harm the tissues of the superior vena cava, and the chemotherapy drugs are quickly and evenly distributed throughout the patient's body. The use of PICCs in the superior vena cava are also commonly used for the infusion of total parenteral nutrition to patients, pressure monitoring of the venous system, and imaging or contrast studies. Depending on the particular treatment being performed, a PICC may remain within the superior vena cava anywhere from less than an hour to more than a year.
One difficulty with the use of PICCs is that the PICC must be navigated and positioned through the venous system to the superior vena cava from outside the patient's body. Thus, the physician has limited means for observing the location of the PICC as it is being navigated and positioned. The most common methods of observing the PICC involve the use of X-rays to view navigation in process or to confirm final positioning. For example, fluoroscopy uses X-rays to provide a video image which can be used to view movement of the PICC or guidewire as it is navigated through the venous system. Alternatively, the PICC may be navigated through the venous system without the use of external visualization by relying on anatomical measurements, tactile feedback during navigation, and physician experience. However, even in this blind type of navigation, an X-ray image is usually taken after navigation is complete to confirm final positioning of the PICC before using the PICC for therapy.
An approach for navigating and positioning a PICC that does not involve the use of X-rays would be desirable since X-ray radiation is dangerous for patients and physicians. One alternative that has been tried is the use of an optical fiber within the PICC that shines light that can be seen through thinner tissues from outside of a patient's body. However, the use of an optical fiber has limited usefulness because final positioning of a PICC occurs within the superior vena cava underneath the sternum where the light from an optical fiber cannot be seen from outside of the patient, both due to the sternum bone blocking the light and the depth of superior vena cava and overlying tissues. Another alternative that has been tried is the use of intravascular ECG to position a PICC within the superior vena cava. However, this technique can only be used for final positioning and cannot be used to navigate a PICC into the superior vena cava, since the readings needed to determine positioning only become noticeably apparent proximate the heart. Thus, in this approach blind navigation has been used to thread the PICC through the venous system to the superior vena cava.
Accordingly, the inventors believe it would be desirable to provide a simple and inexpensive way to navigate and position a catheter without using X-rays.